The present invention relates to an electrical circuit preventing the use of a trainable transmitter if removed from a vehicle.
Trainable transmitters for use in garage door opening applications have become an extremely popular accessory inasmuch as they allow the vehicle owner to eliminate the annoying clip-on transmitter which frequently is sold with a garage door opening system. Further, they are popular inasmuch as they allow reprogramming with vehicle changes, home changes and, therefore, provide the vehicle owner with a garage door opener installed in a vehicle which will adapt to an existing garage door opening receiver. Such remote controls are also employed for security gates and can be employed with home security systems as well. U.S. Pat. No. 5,583,485 discloses such a trainable garage door opening transmitter.
A potential problem exists in that if a vehicle having a transmitter trained to one's security gate, garage door opener or home security system is stolen by, for example, removing a visor into which the garage opening transmitter is installed, the thief potentially could apply power to the visor and utilize the same for gaining unauthorized access. The use of rolling code algorithms by which every actuation of the garage door opening transmitter incrementally changes the code transmitted which is recognized by a synchronized receiver tends to reduce the possibility that such a theft could result in the subsequent successful use of a stolen programmable transmitter. Nonetheless, the potential still remains. A programmable transmitter which utilizes a programmable rolling code is disclosed in U.S. patent application Ser. No. 08/495,101, filed Jun. 27, 1995, and entitled TRAINABLE TRANSMITTER CAPABLE OF LEARNING VARIABLE CODES.